On Tuesday(November 28), all 41 workers who had been confined in the partially collapsed Silkyara Tunnel in the Uttarkashi district of Uttarakhand were successfully freed following a demanding 17-day rescue operation.
The first breakthrough came at 7:56 pm when the first worker came out, and the others followed.
Reaching the trapped workers within the 2-kilometer-long, 8.5-metre-high tunnel presented formidable challenges. Technical difficulties forced a switch to manual drilling to remove the last 10 meters of debris, despite early attempts to use advanced horizontal drilling techniques with an auger machine.
The rescue strategy included vertical drilling and manual excavation, as well as the rat-hole mining method, which was initiated on Monday. Twelve rat-hole mining experts used handheld tools in confined spaces, acknowledging the contentious nature and associated risks of working in narrow underground passages.
Using a steel chute that was inserted into the drilled passage over several days, National Disaster Response Force (NDRF) personnel carried out a methodical extraction.
Prior to the rescue, a dedicated ward with 41 oxygen-supported beds was established at the Chinyalisaur community health center, about 30 kilometers from Silkyara, to accommodate the rescued workers. All possible medical aid and backup plans were also in place in case of an uncalled emergency.
Let us take a closer look at the timeline of the rescue operation, which began in Uttarakhand’s Silkyara Tunnel on Nov 12:
November 12: A landslide at the Silkyara-Dandalgaon tunnel trapped forty-one laborers, prompting an emergency rescue effort.
November 13: CM Pushkar Singh Dhami visited the site and established communication through an oxygen supply pipe.
November 14: Using an auger machine, 800- and 900-millimeter steel pipes were brought in for horizontal digging. But, more debris resulted in two workers suffering minor injuries, which slowed down the work. The stranded workers were provided with food, water, and medication supplies.
November 15: Due to technical dissatisfaction, which resulted in inadequate drilling, the National Handloom Development Corporation Limited (NHIDCL) requested a more advanced auger machine airlifted from Delhi.
November 16: The new drilling machine was assembled and installed, and work continued past midnight.
November 17: Progress halted at 24 meters due to an obstacle that occurred in the fifth pipe; a new auger machine was flown in but ceased operations due to a significant cracking sound emerging from the tunnel.
November 18: Evacuation plans explored, including alternative methods like vertical drilling, to bring the 41 stranded workers out of the tunnel.
November 19: Drilling activities remained suspended for the day, with Minister Nitin Gadkari emphasizing potential success with horizontal drilling.
November 20: PM Modi assessed operations, spoke to CM Dhami and emphasized the importance of keeping morale high among all the rescue team.
November 21: Rescuers released the first video, which showed the stranded labourers in the Silkyara tunnel interacting and receiving supplies through the pipeline. Drilling for a backup tunnel on the Char Dham route started at the Balkot end at the same time.
November 22: Drilling horizontally advanced to 45 meters, but in the evening, iron rods blocked the way.
November 23: After the obstruction was removed, the process resumed and progressed to 48 meters before stopping because of cracks appearing in the drilling machine's resting platform.
November 24: After restarting operations, drilling was halted due to an obstruction in the auger machine, possibly a metal object.
November 25: Tunneling expert Arnold Dix suggested manual or vertical drilling after the auger machine malfunctioned.
November 26: The Silkyara-Barkot tunnel is 86 meters below the surface, so rescuers had to drill 86 meters into the hill above it. 19.5 meters of drilling was already done by the evening, followed by two BRO officials having sustained injuries.
November 27: To remove the last bit of debris, a dozen rat-hole mining experts started manual drilling.
November 28: After manual drilling, a pipe put into the tunnel reached the breakthrough point at 57 meters, allowing for the safe and orderly evacuation of every worker by Tuesday night at 7:56 p.m.
(With agency inputs)
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